1. Field of the Invention
Embodiments of this invention relate generally to printed-circuit board (PCB) connectors, and in particular embodiments, to methods and devices for coupling electrical conductors of physically separate electrical circuits by utilizing pre-loaded leaf-spring elements that exert increased spring forces when compressed by mating conductors, resulting in decreased ohmic resistance between the leaf-spring elements and the mating conductors, and systems incorporating the same.
2. Description of Related Art
In many electronic devices and systems, electrical circuitry is not confined to a single physical structure such as a PCB, but extends over multiple PCBs or other components. While hard-wiring physically dispersed electrical circuitry together with permanent connections such as soldered wires will suffice electrically, such methods of assembly are often impractical from a production or maintenance standpoint. Assembly or disassembly can often be more efficiently achieved by providing connectors on each physically distinct structure which are capable of being mated together or with other components to make the necessary electrical connections, or conversely, de-mated for repairs, maintenance, or upgrades.
Conventional PCB connectors often take the form of pin-and-socket arrangements, where multiple pins in one connector are physically inserted into multiple sockets in another connector. The compressive forces of the socket against the pin makes the physical and electrical connection. Pin-and-socket connectors also generally provide good protection for the pins and sockets, which are often recessed within their separate connector housings to provide protection in both the uncoupled and coupled configurations. However, the friction of the sockets against the pins necessitates high insertion and removal forces, making automated assembly difficult.
Pin-and-socket connectors are often a poor choice when centrally located on PCBs, or in any instance where surface mounting of components is desired to eliminate the need for through-mounting holes or vias which interfere with the routing of circuit traces within the PCB. While certain pin-and-socket connectors can be surface-mounted to eliminate through-mounting vias, their high insertion forces cause other problems. When connectors are surface mounted to the PCB, their solder connections may be an integral part of their securement to the PCB, and mating or de-mating of high insertion force surface mounted pin-and-socket connectors may result in mechanical stress and damage to the solder connections. In extreme cases;, these forces may cause the entire surface mounted connector to be pulled off the PCB. In addition, pin-and-socket connectors require precise alignment, and when several such connectors are located on a PCB, manufacturing and assembly tolerances may prevent the proper mating of all connectors.
Conventional leaf spring connectors solve some of the problems of pin-and-socket connectors. Leaf-spring connectors typically have flat rectangular blades or contacts which protrude above the surface of the connector when unloaded. A spring force is encountered by the blades of a mating connector when compressing the leaf-spring elements. The spring force of the leaf-spring element against the mating connector blades makes the physical and electrical connection. Minimal force is needed to deflect the leaf-spring element from its unloaded position, and thus assembly is simplified. Depending on how the leaf-spring element is formed, these low connection forces may place less mechanical stress on the solder joints of the connector. Additionally, leaf-spring elements are necessarily wide and flat to create the desired spring action, and such contacts are more tolerant of positional errors during assembly.
However, leaf-spring connectors are not without problems. The protrusion of the leaf-spring elements above the connector housing increases the vulnerability of the leaf-spring element to damage caused by snagging other structures during, for example, manufacture, transportation, and installation. In addition, the small forces typically needed to deflect the leaf-spring element from its unloaded position, while desirable from an assembly standpoint, may also lead to increased corrosion of the contacts, high ohmic resistance, and a poor electrical connection, especially in high current applications.